SINGAPORE, April 12 (Reuters) - A mutual health aid plan launched by Ant Financial Services Group, the dominant fintech player in China, has amassed more than 50 million users and is aiming for 300 million within two years, the company said late on Thursday.

The plan, dubbed Xiang Hu Bao or literally "mutual protection", is marketed on Ant Financial's flagship mobile payment app Alipay and provides participants a basic medical coverage with the risks and expenses distributed across all members.

It has gained unexpected popularity among China's "low-end population", poorer sections of society, who struggle to afford medical services due to the government's inadequate social healthcare system and are under-served by traditional commercial insurers as they cannot meet the premiums and advance payments required with commercial health insurance products.

Chinese billionaire Jack Ma's Ant Financial was spun off from e-commerce giant Alibaba Group Co Ltd, which went public in 2014, and has played a vital role in shaping the financial technology landscape in China, shaking up the state-controlled traditional banking, asset management and insurance sectors with disruptive new products.

The expansion of Xiang Hu Bao was even faster than Ant Financial's blockbuster online spare cash management platform Yu'e Bao, which took more than six months to reach the 50 million user milestone after launching in 2013 and has grown to become the world's largest money market fund with 1.13 trillion yuan ($168.2 billion) in net asset as of end-2018. China has a population of nearly 1.4 billion.

The Xiang Hu Bao health plan protects participants against 100 critical illnesses with a one-time payout of up to 300,000 yuan ($44,650). The cost is shared equally by all other participants, capped at 188 yuan per month for individual users in 2019, according to its description.

Despite its mutual insurance features, Ant Financial said the plan is "not a health insurance product", indicating the product is not regulated by the country's insurance regulator.